CN102130746B - Network coding feedback method for coordinated multi-point transmission system - Google Patents

Abstract

The invention discloses a network coding feedback method for a coordinated multi-point transmission system, which belongs to the technical field of communication. Information such as pre-coding matrix indicator (PMI) information required to be fed back and own information such as reference signal (RS) information periodically to be transmitted are subjected to network coding and then transmitted. A network coding concept is introduced to simultaneously transmit feedback information under the condition of keeping constant conventional uplink transmission overhead. A transmitted information sequence subjected to the network coding still has relatively higher cross correlation and autocorrelativity, so a receiver obtains the PMI information by a correlation detection and minimum Euclidean distance searching method, and own information required to be fed back is hidden in a sounding RS (SRS) sequence subjected to the network coding in a network coding way by taking SRS information required to be transmitted by the system as a carrier to improve the transmission effectiveness and effectively improve the throughput of the system by reducing even eliminating feedback overhead.

Description

Network code feedback method in multipoint cooperative transmission system

Technical field

The present invention relates to the feedback transmission scheme in a kind of communication system, be specifically related to a kind of network code feedback method that reduces system feedback expense under keeping system transmission reliability basis, belong to communication technical field.

Background technology

In coordinated multipoint transmission (CoMP) system, the design of feedback scheme has very large impact to systematic function, and various implicit feedback, demonstration feedback and the feedback scheme based on SRS (Sounding RS) are the focuses that each major company is discussed at present.In the design process of various feedback schemes, feedback overhead is very important Consideration, need under the prerequisite that as far as possible reduces feedback overhead, keep the few degeneration of trying one's best of feedback scheme performance, in implicit feedback scheme, generally feedback information is limited in to precoding vector index or the code book index of limited bit.

In any case but compressed feedback amount, feedback information all needs independent transmission, and this can increase extra feedback burden undoubtedly.Can in the situation that keeping existing up link transmission expense constant, transmit feedback information so simultaneously?

The feedback of coding Network Based can address this problem.In feedback procedure, user terminal (UE) will need feedack (as PMI information) send after doing network code with self fixing information (as RS information) that will send, separablely after receiving terminal decoding go out former transmission information and feedack.

LTE physical layer has defined two kinds of up RS:

(1) demodulation RS (DMRS:Demodulation RS), is mainly used in the coherent demodulation in channel estimating;

(2) survey RS (SRS:Sounding RS), be not associated with upstream data and control transmission, for determining channel quality, thereby in up link, carry out frequency selective scheduling.

Adopt has weighing apparatus envelope zero auto-correlation (Constant Amplitude Zero Auto-Correlation more at present, CAZAC) sequence of characteristic is as uplink reference signals (DMRS/SRS) sequence, DMRS is along with data or control information send together, and its resource location (time and frequency) is determined by corresponding shared channel or control channel.And the transmission of up Sounding reference signal and uplink physical channel are irrelevant, be up channel independently, according to the predefined cycle, terminal sends on the frequency domain position that need to carry out channel measurement.The network code of discussion of the present invention refers to after UE end is done network code by PMI with SRS and obtains sequence SRS ePMI ', and fed back to eNB (base station) end; ENB receives and draws SRS ePMI ' after network code in all PMI situations is compared afterwards, and draws former PMI information.

Summary of the invention

For the larger problem of existing feedback scheme feedback overhead in CoMP system, the present invention proposes a kind of mistake under system reliability prerequisite, can largely reduce the network code feedback method of (eliminating even completely) feedback overhead.In order to improve system effectiveness, reduce feedback overhead, the present invention introduces network code thought, at UE place, the PMI ' sequence after uniform enconding and SRS sequence is carried out to mould 2 XORs.

Base station eNB 1 and eNB2 are user UE service simultaneously.After a downlink transmission, UE, except sending the pilot frequency information (being SRS sequence) of eNB1, also will feed back to eNB1 by the PMI information of eNB2 link.The SRS sequence that has N kind to be produced by different radical exponents in the armed SRS arrangement set of known UE, each other complete quadrature.

To achieve these goals, the network code feedback method described in technical scheme of the present invention in multipoint cooperative transmission system, comprises the following steps:

Step 1, by 2 of user UE ^kthe individual PMI information that may need to feed back to the eNB2 link of eNB1 is carried out Linear block coding, is about to 2 ^kthe PMI of individual k bit _i(i=0,1 .., 2 ^k-1) carry out Linear block coding, be mapped as 2 ^kthe long sequence of individual length L bit, is designated as PMI ' _i; L is the length of SRS sequence;

For example, when k=4, PMI _ihave 16, i from 0 to 15 value; That each user UE transmits is a PMI in these 16 certainly _i, k is predefined according to systematic function requirement, k is longer, PMI _ithe information of carrying is just more;

Step 2, each PMI ' according to the following formula step 1 being obtained _icarry out network code with each SRS sequence in the armed SRS arrangement set of user UE:

${\mathrm{SRS}}_{\mathrm{NC}}^i=\mathrm{SRSe}{\mathrm{PMI}}_i^{\′},i=\mathrm{0,1},...,2^k-1---\left(1\right)$

And PMI ' described SRS arrangement set comprises N SRS sequence, and the length of each SRS sequence is L, _iequal in length, each transmission only needs to transmit a SRS sequence, length L is required to determine by real system;

By N * 2 that obtain ^kindividual network code code word

as the codeword set S of network code, and set up a corresponding code table, for storing, form each network code code word of this set

corresponding SRS and PMI _i;

Network code computing ⊙ described herein carries out XOR to two binary sequences, obtains new " 01 " sequence after network code.

As preferably, SRS sequence described herein is the pilot frequency information of user UE eNB1 to be sent.

The SRS sequence that has N kind to be produced by different radical exponents in the armed SRS arrangement set of described user UE, each other complete quadrature.

Step 3, user UE is according to the current PMI that need to feed back to the eNB2 link of eNB1 _q, and current armed SRS sequence, the code table of setting up from step 2, search corresponding network code code word

and by this

through ovennodulation, backward eNB1 sends, and eNB1 receives and be stored as sequence

wherein, q is 0 to 2 ^kany one integer in-1 (containing border) is identical with i span; When can keeping synchronously (be transmitting terminal also can invocation step 2 code tables of setting up) at communicating pair, this situation can save very large amount of calculation, need not launch at every turn and all encode and XOR, table look-at just can obtain corresponding network code code word

Or at UE place by PMI _icarry out Linear block coding and obtain PMI ' _qsequence, then by PMI ' _qcarry out the network code as described in step 2 with current armed SRS sequence, generate

and by this

through ovennodulation, backward eNB1 sends, and eNB1 receives and be stored as sequence

this situation is applicable to the system that communicating pair cannot keep synchronously (be transmitting terminal can not invocation step 2 code tables of setting up).

Step 4, eNB1 is in N * 2 of the codeword set S of network code ^kin individual network code code word, search for, with the code word receiving

compare, according to following principle, estimate the actual sequence sending:

$\stackrel{2}{S}{\mathrm{RS}}_{\mathrm{NC}}^q=\arg \underset{{\mathrm{SRS}}_{\mathrm{NC}}^i\∈S}{\min }{\left|\right|{\mathrm{SRS}}_{\mathrm{NC}}^i-{\mathrm{SRS}}_{\mathrm{NC}}\left|\right|}_F^2,i=\mathrm{0,1,2},...,2^k-1---\left(2\right)$

In formula, S is the codeword set after the network code set up of step 2,

for Frobenius norm square-be handle here with

be used as that vector processes.Above formula reality be exactly will be in S set these N * 2 ^kin individual possible network code code word, find one with

the network code that sequence Euclidean distance is nearest, both make the sequence vector mould value minimum obtaining after difference operation.Wherein

n * 2 in unique corresponding S set ^kone of individual network code code word finds this network code that makes norm squared minimum just to mean to have found the PMI of the actual transmission of user UE simultaneously _qsequence and SRS sequence;

Note, in step 3

the network code sequence that represents the actual transmission of UE, in step 4

represent the network code sequence that UE that receiving terminal is estimated sends, in the situation that being free from mistakes, both are the same, have and under error situation, are likely mistaken for another network code.

Step 5, determines

after, the code table of setting up according to step 2 (is all possible SRS sequence and all possible PMI ' _ithe network code codeword table that sequence XOR obtains) find corresponding SRS and PMI ' _q.Due in advance to PMI _iwhat do is Linear block coding, so find the code word PMI ' in code table _qonly need to get grouping code word PMI ' later _qfront k position be PMI _q.

As preferred scheme, in step 1, the k position PMI information of pending Linear block coding is that the information that need to transmit according to real system determines, but the PMI ' to L position by k position PMI sequence mapping (being uniform enconding) how _isequence but has different mapping code rules.The present invention, by computer search, has obtained 2 ^keach k position PMI sequence mapping of individual k position PMI sequence is encoded into the PMI ' of L position _ithe best mapping code rule of sequence.The principle of search is according to this mapping code rule, makes to need after the k position PMI information sequence of the transmission Linear block coding described in carry out step 1, then carries out the resulting code word of network code with SRS

should there is good autocorrelation and cross correlation, when guaranteeing that network code code word still has good autocorrelation and cross correlation, can utilize in codeword set S

according to conventional method, at the reception signal being interfered, the signal that extracts matched base stations in the signal Y in following formula (can disturb the signal formation of adjacent cell reception around when community transmits) is analyzed, and obtains channel condition information.Illustrate theoretically that the network code feedback method that the present invention proposes has actual operability, can be used for distinguishing the signal of different user below.

Generally, at the receiving terminal of certain community, signal can be subject to the interference of other different districts, with Y, represents to receive signal, total n community, X _jthe signal that represents j community transmitting, network code code word

be PMI ' _me SRS _j, the recognition sequence of j community of expression, wherein PMI ' _mfor the PMI sequence of needs feedback is carried out the sequence after linear block encoding, m ∈ 0,1,2 ..., 2 ^k-1}, SRS _jfor not carrying out the completely orthogonal SRS sequence before network code, j ∈ 1,2 ..., n}; Different between sequence, there is good autocorrelation and cross correlation (as shown in Figure 5), utilize this character for finding oneself matched signal in different base stations.

$Y=X_{1}e{\mathrm{SRS}}_1^m+...+X_{j}e{\mathrm{SRS}}_j^m+...+X_{n}e{\mathrm{SRS}}_n^m$

At place, j base station, in order to extract the signal X of j community transmitting _j, by autocorrelation and the cross correlation of network code code word, therefore only need Y to received signal to do XOR,

$\mathrm{Ye}{\mathrm{SRS}}_j^m=(X_{1}e{\mathrm{SRS}}_1^m+...+X_{j}e{\mathrm{SRS}}_j^m+...+X_{n}e{\mathrm{SRS}}_n^m)e{\mathrm{SRS}}_j^m=X_j$

Contrast prior art, beneficial effect of the present invention is, communication source is keeping, under the prerequisite of communication reliability, by reducing even to eliminate feedback overhead, improving transmission availability.The introducing of network code thought can transmit feedback information in the situation that keeping existing up link transmission expense constant simultaneously.Because the transmission information sequence after network code still has good cross correlation and autocorrelation, at receiving terminal, can obtain PMI information by coherent detection the way of finding minimum euclidean distance, further can add to make an uproar information sequence and do not add the information source transmission information sequence of making an uproar and obtain channel quality estimation value by what receive later.System is take in the present invention, and originally to need the SRS information of transmission be carrier, the mode that self needs feedack by network code is hidden in the SRS sequence after network code, can reduce or eliminate unavoidable feedback burden in (length by PMI sequence with respect to SRS sequence determines) conventional feedback schemes completely, thereby effectively improving throughput of system.

Accompanying drawing explanation

Fig. 1 is the feedback model figure of the coding Network Based selected of the present invention;

The CoMP grid encoder feedback scheme that Fig. 2 designs for the present invention;

Fig. 3 be the present invention by computer search to coding after have the PMI ' of better cross correlation _icode book figure;

Fig. 4 is the PMI decoding error rate figure obtaining under the present invention program;

Fig. 5 is 36 bit lengths after the network code selected of the present invention

the correlation curve chart of sequence.

Embodiment

For making object, technical scheme and the advantage of invention clearer, below in conjunction with accompanying drawing, embodiments of the present invention is described in detail.The present embodiment is implemented as prerequisite take invention technical scheme, provided detailed execution mode and specific operation process, but protection scope of the present invention is not limited to following embodiment.

As shown in Figure 1, for user UE service, (the present invention is only limited to the situation of a UE of two base station services simultaneously for base station eNB 1 and eNB2, and two base stations are UE service simultaneously, sequential in no particular order, two different transmission only take a time slot, can improve throughput of system, this advantage place that this patent proposes a plan just).After a downlink transmission, UE, except sending the pilot frequency information (being SRS sequence) of eNB1, also will feed back to eNB1 by the PMI information of eNB2 link.The SRS sequence that has N kind to be produced by different radical exponents in the armed SRS arrangement set of known UE, each other complete quadrature.

UE need to transmit the PMI of a k position at every turn as mentioned above _isequence and a SRS sequence, that the present invention will do is exactly this PMI that finds out user UE transmission _iwith corresponding SRS; Possible PMI _isequence has 2 ^kkind, by by all PMI _inetwork code result corresponding to sequence compares one by one with the sequence receiving, the most similar with which, just thinks which PMI _i, the PMI transmitting _isequence is ignorant for receiving terminal, and receiving terminal is only known all possible situation, takes the mode comparing one by one to find most possible result as final solution.

In communication system, information source, except transmitting the needed information of the stay of two nights, also needs to feed back self distinctive information.Existing explicit feedback, implicit feedback or the feedback scheme based on SRS (Sounding RS), in any case compressed feedback amount, feedback information all needs independent transmission, this can increase extra feedback burden undoubtedly.And the introducing of network code thought can transmit feedback information in the situation that keeping existing up link transmission expense constant simultaneously.Concrete grammar is to send needing feedack (as PMI information) and self the fixing information (as RS information) that will send first to carry out network code again.Because the transmission information sequence after network code still has good cross correlation and autocorrelation, at receiving terminal, can obtain PMI information (as shown in Figure 2) by coherent detection the way of finding minimum euclidean distance.

The network code of discussion of the present invention refers to after UE end is done network code by PMI with SRS and obtains sequence SRSe PMI ', and fed back to eNB (base station) end; ENB receives and draws SRS ePMI ' after network code in all PMI situations is compared afterwards, and draws former PMI information.

It should be noted that, because the PMI information sequence length of needs transmission is different with SRS sequence length, at both, doing before network code operation must be the sequence PMI ' isometric with SRS sequence by relatively short PMI sequence mapping, and the SRS ' sequence that makes PMI ' after shining upon and SRS sequence do to obtain after network code has good their cross correlation.In order simply to extract original PMI information at receiving terminal, the present invention adopts system linearity block code to realize the mapping one by one from PMI sequence to PMI ', and specifically the way by computer search finds and can meet the PMI ' code that has better their cross correlation after network code.From preliminary simulation result, can find, PMI information is done after network code with SRS sequence, at receiving terminal, can restore well feedback information PMI.

Without loss of generality, the present embodiment is established SRS length L=36, PMI length k=4, and possible SRS sequence has three kinds, i.e. N=3.

Step 1, goes out best coding rule at UE place according to computer search, and the PMI sequence that is 4 to length is done Linear block coding mapping, obtains the PMI ' that length is 36bit _isequence, 2 of correspondence ⁴the Linear block coding code table of=16 kinds of PMI as shown in Figure 3.

Forced coding rule is herein to make PMI carry out after Linear block coding, then carries out the resulting code word of network code with SRS and still have good autocorrelation and cross correlation.

In Fig. 3, Mapping is totally 16 row 36 row, and code word of each behavior, is respectively PMI ₀=[0 00 0] are to PMI ₁₅the Linear codes code word that=[1 11 1] are corresponding.These code words are to have computer search to obtain, and keep as far as possible equating of Hamming distance between the heavy and code word of code.In fact, the codewords weight of front 14 row is 18, and latter two codewords weight is 17, and these 16 Linear codes code words Hamming distance is each other between 16 to 20.According to coding rule shown in Fig. 3, PMI sequence is carried out after Linear block coding, then carry out the resulting code word of network code with SRS and still there is good autocorrelation and cross correlation;

Step 2, UE is to the SRS sequence of 36 bits and the PMI ' that step 1 obtains of being equal in length _isequence is done network code computing,

${\mathrm{SRS}}_{\mathrm{NC}}^q={\mathrm{SRS}}^{q}e{\mathrm{PMI}}_i^{\′}=({\mathrm{SRS}}_1^{q}e{\mathrm{PMI}}_{i1}^{\′},{\mathrm{SRS}}_2^{q}e{\mathrm{PMI}}_{i2}^{\′},...,{\mathrm{SRS}}_t^{q}e{\mathrm{PMI}}_{\mathrm{ij}}^{\′}...,{\mathrm{SRS}}_{36}^{q}e{\mathrm{PMI}}_{i36}^{\′}),$

SRS in above formula ^qrepresent that the length that need to send is the SRS sequence to be sent of 36,

represent SRS ^qin t position bit, t ∈ 1,2 ... 35,36}; PMI ' _irepresent in sequence after 16 possible PMI uniform encondings to be sent, i ∈ 0,1 ..., 15}, and PMI ' _ij{ 0,1} represents PMI ' to ∈ _ij position bit in sequence, j ∈ 1,2 ... 35,36}.

By 3 * 2 of acquisition ⁴=48 network code code words

as the codeword set S of network code, and set up a corresponding code table, for storing, form each network code code word of this set

corresponding SRS and PMI _i;

Step 3, user UE is according to the current PMI that need to feed back to the eNB2 link of eNB1 _q, and current armed SRS sequence, the code table of setting up from step 2, search corresponding network code code word and by this

through ovennodulation, backward eNB1 sends, and eNB1 receives and be stored as sequence

wherein, q is any one integer in 0 to 15 (containing border), identical with i span;

Or when transmitting terminal can not invocation step 2 set up code table time, at UE place by PMI _icarry out Linear block coding and obtain PMI ' _qsequence, then by PMI ' _qcarry out the network code as described in step 2 with current armed SRS sequence, generate and by this

through ovennodulation, backward eNB1 sends, and eNB1 receives and be stored as sequence

Step 4, eNB1 searches for by all possible 3 kinds of SRS sequences and all possible 16 kinds of PMI ' _isequence XOR can obtain 3 * 2 ⁴=48 network code code words.By these 48 network code code words with connect the code word obtaining relatively, find out with

one of them code word that has minimum euclidean distance think the sequence of actual transmission:

$\stackrel{2}{S}{\mathrm{RS}}_{\mathrm{NC}}^q=\arg \underset{{\mathrm{SRS}}_{\mathrm{NC}}^i\∈S}{\min }{\left|\right|{\mathrm{SRS}}_{\mathrm{NC}}^i-{\mathrm{SRS}}_{\mathrm{NC}}\left|\right|}_F^2,i=\mathrm{0,1,2},...,2^4-1$

Step 5, determines after, according to code table, (be all possible 3 kinds of SRS sequences and all possible 16 kinds of PMI _ithe network code codeword table that sequence XOR obtains) find corresponding PMI _i.

Because the linear block codes of searching for out by computer programming can guarantee after network code

still there is good cross correlation and autocorrelation (as shown in Figure 5), so can utilize, obtain

the signal that extracts matched base stations according to conventional method in the signal being interfered (can disturb the signal formation of adjacent cell reception around when community transmits) is analyzed, and obtains channel condition information.

According to code word in Mapping above, SRS is carried out network code and carries out simulation analysis, Fig. 4 has provided the effect of recovering PMI after network code at receiving terminal, only right in simulation model

add the interference of white Gaussian noise.The PMI number that PMI decoding error rate refers to decoding error shared ratio in total PMI; SNR is the ratio of signal power (SRS is permanent good fortune sequence, is distributed on unit circle, and power is 1) to noise power.As can be seen from Figure 4, the present invention has good transmission reliability.

And will guarantee that receiving terminal can be distinguished, extract with it corresponding signal, need to guarantee the good their cross correlation of sequence after coding.Below the separately impact on SRS sequence dependent features after research network code.

Get three SRS sequences

with

corresponding radical exponent is respectively q1=25, q2=29 and q3=34.Sequence

follow

with

correlation properties be designated as respectively R _1-1, R _1-2and R _1-2.Network code is used sequence to produce at random, and the sequence after coding is designated as

with

During sequence length L=36, before and after network code, SRS sequence dependent features is shown in Fig. 5, in figure, drawn q=25, the autocorrelation performance curve (as shown in band " o " the type curve that ordinate in Fig. 5 reaches 1) that network code code word during PMI=0000 is relevant from himself and (be with " o " with the cross-correlation performance curve of the different code words of other all possible 3 * 16-1=47 kinds, " * ", " x " type curve represents respectively three different radical exponent q ₁=25, q ₂=29 and q ₃the Sequence Operation Theory result of=34 correspondences).

As shown in Figure 5, before and after network code, the autocorrelation curve of SRS sequence has obvious impulse at 0,

with

one of cross correlation value maintain below 0.4, that is to say between the different SRS codeword sequences after network code and still can be distinguished by correlation properties.In fact, what do that network code uses for former SRS here is random bit sequence, if can design Linear codes code word, can obtain better their cross correlation.

Fig. 5 shows: after network code

still there is good cross correlation and autocorrelation, so can extract according to conventional method the signal of matched base stations in the signal being interfered, analyze, obtain channel condition information.

Above-described specific descriptions; object, technical scheme and beneficial effect to invention further describe; institute is understood that; the foregoing is only specific embodiments of the invention; the protection range being not intended to limit the present invention; within the spirit and principles in the present invention all, any modification of making, be equal to replacement, improvement etc., within all should being included in protection scope of the present invention.

Claims (8)

1. the network code feedback method in multipoint cooperative transmission system, base station eNB 1 and eNB2 for user UE service, is characterized in that simultaneously, comprise the following steps:

Step 1, by 2 of user UE ^kthe individual PMI information that may need to feed back to the eNB2 link of eNB1 is carried out Linear block coding, is about to 2 ^kthe PMI of individual k bit _icarry out Linear block coding, be mapped as 2 ^kthe long sequence of individual length L bit, is designated as PMI _i'; Wherein L is the length of SRS sequence, i=0, and 1 ..., 2 ^k-1; K is predefined according to systematic function requirement, and k is longer, PMI _ithe information of carrying is just more;

Step 2, each PMI according to the following formula step 1 being obtained _i' carry out network code with each the SRS sequence in the armed SRS arrangement set of user UE:

And PMI described SRS arrangement set comprises N SRS sequence, and the length of each SRS sequence is L, _i' equal in length, each transmission only needs to transmit a SRS sequence, length L is required to determine by real system; Network code computing ⊙ described herein carries out XOR to two binary sequences, obtains new " 01 " sequence after network code;

By N * 2 that obtain ^kindividual network code code word

as the codeword set S of network code, and set up a corresponding code table, for storing, form each network code code word of this set

corresponding SRS and PMI _i;

Step 3, user UE is according to the current PMI that need to feed back to the eNB2 link of eNB1 _q, and current armed SRS sequence, the code table of setting up from step 2, search corresponding network code code word

and by this through ovennodulation, backward eNB1 sends, and eNB1 receives and be stored as sequence SRS _nC; Wherein, q is 0 to 2 ^kany one integer in-1 is identical with i span;

Step 4, eNB1 is these N * 2 in the codeword set S of network code ^kin individual possible network code code word, find one with the code word SRS receiving _nCthe network code that sequence Euclidean distance is nearest, according to following principle, estimate the actual sequence sending:

${\mathrm{SRS}}_{\mathrm{NC}}^q=\arg \underset{{\mathrm{SRS}}_{\mathrm{NC}}^i\∈S}{\min }{\left|\right|{\mathrm{SRS}}_{\mathrm{NC}}^i-{\mathrm{SRS}}_{\mathrm{NC}}\left|\right|}_F^2,i=\mathrm{0,1,2},...,2^k-1---\left(2\right)$

In formula, S is the codeword set after the network code set up of step 2,

for Frobenius norm square; Wherein

n * 2 in unique corresponding S set ^ka network code of individual network code code word, makes norm squared minimum;

Step 5, determines after, the code table of setting up according to step 2 finds corresponding SRS and PMI ' _q; Get this grouping code word PMI ' _qfront k position be PMI _q.

2. the network code feedback method in a kind of multipoint cooperative transmission system according to claim 1, is characterized in that, described SRS sequence is the pilot frequency information of user UE eNB1 to be sent.

3. according to the network code feedback method in a kind of multipoint cooperative transmission system described in claim 1 or 2, it is characterized in that the SRS sequence that has N kind to be produced by different radical exponents in the armed SRS arrangement set of described user UE, each other complete quadrature.

4. according to the network code feedback method in a kind of multipoint cooperative transmission system described in claim 1 or 2, it is characterized in that, step 3 adopts following scheme: at UE place by PMI _icarry out Linear block coding and obtain PMI ' _qsequence, then by PMI ' _qcarry out the network code as described in step 2 with current armed SRS sequence, generate

and by this

through ovennodulation, backward eNB1 sends, and eNB1 receives and be stored as sequence SRS _nC.

5. the network code feedback method in a kind of multipoint cooperative transmission system according to claim 3, is characterized in that, step 3 adopts following scheme: at UE place by PMI _icarry out Linear block coding and obtain PMI ' _qsequence, then by PMI ' _qcarry out the network code as described in step 2 with current armed SRS sequence, generate

and by this

through ovennodulation, backward eNB1 sends, and eNB1 receives and be stored as sequence SRS _nC.

6. according to the network code feedback method in a kind of multipoint cooperative transmission system described in claim 1 or 2, it is characterized in that, in step 1, the k position PMI information of pending Linear block coding is that the information that need to transmit according to real system determines, by this 2 ^keach k position PMI sequence mapping of individual k position PMI sequence is encoded into the PMI of L position _ithe best mapping code rule of ' sequence is, makes to need after the k position PMI information sequence of the transmission Linear block coding described in carry out step 1, then carries out the resulting code word of network code with SRS

should there is good autocorrelation and cross correlation.

7. the network code feedback method in a kind of multipoint cooperative transmission system according to claim 3, is characterized in that, in step 1, the k position PMI information of pending Linear block coding is that the information that need to transmit according to real system determines, by this 2 ^keach k position PMI sequence mapping of individual k position PMI sequence is encoded into the PMI of L position _ithe best mapping code rule of ' sequence is, makes to need after the k position PMI information sequence of the transmission Linear block coding described in carry out step 1, then carries out the resulting code word of network code with SRS

should there is good autocorrelation and cross correlation.

8. the network code feedback method in a kind of multipoint cooperative transmission system according to claim 4, is characterized in that, in step 1, the k position PMI information of pending Linear block coding is that the information that need to transmit according to real system determines, by this 2 ^keach k position PMI sequence mapping of individual k position PMI sequence is encoded into the PMI of L position _ithe best mapping code rule of ' sequence is, makes to need after the k position PMI information sequence of the transmission Linear block coding described in carry out step 1, then carries out the resulting code word of network code with SRS

should there is good autocorrelation and cross correlation.

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